During my forced time off from my rewrite, something occurred to me about a moment in my WiP2 that's going to be a bit problematic. It's one of those watershed moments where a character makes a choice that will determine the course his life will take. So it makes for excellent story.Only... the motivation was off. Or more accurately, the perception of the motivation was off.
To my mind, characterization is the reason why a character is who he is. Motivation is the reason why a character does what he does.
Actually, it's more the reason behind the reason. For example, commitment phobia might be a reason why a guy won't marry, but the reaction that caused the phobia as a result of something in the past is the motivation. In the case above, distrust as a result of his wife cheating on him with his best man would be his motivation.
Characters can have more than one motivation, but most importantly, each motivation will have a significant effect on how the character reacts to others or on how he lives and sees life. For example, Mr. Commitment-Phobe might start distrusting women in general, and then struggle with the idea of marriage as he falls in love. But then, since he was betrayed, he'll also very likely struggle to trust his love-interest around his friends or vice versa.
It's vitally important that the motivation is carried through the character as far as it can conceivably go, because if it doesn't go all the way, the motivation will be seen as weak and it will impact on the story. If I stumbled over the above example in the story, I would think that his phobia was on over-reaction if he didn't show at least some indication of it when his love interest is talking with his best friend. If this didn't happen, it cheapens the situation and takes the depth out of the story.
Another important factor to consider: perception vs reality. What I mean with this is the reader's perception based on the character's actions vs. the actual reason behind the action as known to the author. It's not that common that a character's motivation is kept from the reader until the end of the story, since the conflict that comes as a result of character motivations can make for some wonderful story, because the journey of discovery of the character's motivation makes for good reading. But not if the reader leaps to the wrong conclusion as to what motivates a character.
If the reader decides that a reader won't marry because he's selfish in some way, there's a problem. Because whether or not this conclusion was wrong, it will affect how the reader will perceive the story's events, as well as whether he/she will be able to stick through the story all the way to the big reveal.
The reader can be kept on the right track, though, through leaving clues to the motivation or by showing that the opposite of the wrong conclusion is true. For example, if there's a chance of a reader thinking that Mr. Commitment-Phobe is nothing but a selfish bastard, show him at his most generous. Maybe let him take a kid under his wing. Something like that. Something that shows that not only is the guy generous, he's only worried about committing to a woman.
What about you? How do you handle motivation - especially for difficult characters?